A gas turbine engine may be used to power various types of vehicles and systems. A particular type of gas turbine engine that may be used to power aircraft is a turbofan gas turbine engine. A turbofan gas turbine engine may include, for example, five major sections, a fan section, a compressor section, a combustor section, a turbine section, and an exhaust section. The fan section is positioned at the front, or “inlet” section of the engine, and includes a fan that induces air from the surrounding environment into the engine, and accelerates a fraction of this air toward the compressor section. The remaining fraction of air induced into the fan section is accelerated into and through a bypass plenum, and out the exhaust section producing much of the thrust.
The compressor section raises the pressure of the air it receives from the fan section to a relatively high level. In a multi-spool engine, the compressor section may include two or more compressors. For example, in a triple spool engine, the compressor section may include a high pressure compressor, and an intermediate compressor. The compressed air from the compressor section then enters the combustor section, where a ring of fuel nozzles injects a steady stream of fuel. The injected fuel is ignited by a burner, which significantly increases the energy of the compressed air.
The high-energy compressed air from the combustor section then flows into and through the turbine section, causing two or more rotationally mounted turbines to rotate and generate energy. As the turbines rotate, each drives equipment in the engine via concentrically disposed shafts or spools. For example, one or more turbines may drive one or more compressors in the compressor section, and one turbine typically drives the fan. The air exiting the turbine section is exhausted from the engine via the exhaust section, and the energy remaining in this exhaust air aids the thrust generated by the air flowing through the bypass plenum.
The fan in a turbofan engine is generally composed of many rotor blades and stator vanes. During engine operation, the blades rotate, while the stator vanes remain stationary. In a typical configuration, the fan section may include a plurality of sets or rows of rotor blades and stator vanes along the axial length of an air intake path of generally annular shape.
It is well known that in turbofan engines, abrasive particles, such as sand or dust, act as an abrasive upon impact and may cause erosion of the materials forming component engine parts. In the case of composite static stator vanes found directly behind the fan blades, wear by erosion to the leading edges of the static stator vanes leads to deterioration of the performance characteristics of the engine.
Current composite stator vanes are constructed to include a stainless steel mesh screen disposed over a composite epoxy resin system. Over time, a portion of stainless steel mesh proximate the leading edge of the stator vane may erode and/or become delaminated from the composite epoxy resin. Additionally, the composite epoxy resin may also erode and may leave the mesh unsupported. Eventually, the stainless steel mesh may split and open up causing a flow disturbance in the fan bypass path which may result in degraded performance and loss of engine thrust.
Accordingly, it is desirable to provide for an improved stator vane that includes leading edge erosion protection. In addition, it is desirable to extend the life of a composite stator vane in light of abrasive damage to the leading edge of the stator vane. Finally, it is desired to provide a method for preventing erosion to the leading edge of the stator vane that is less costly as compared to the alternative of replacing the damaged stator vane with a new one. The present invention addresses one or more of these needs.